Inhibitory activity of Dodonaea viscosa var. angustifolia extract against Streptococcus mutans and its biofilm

Ethnopharmacological relevance

The leaves of Dodonaea viscosa var. angustifolia (DVA) are traditionally used for the treatment of fever, colds, oral thrush, toothaches and related problems. Streptococcus mutans is implicated in many oral infections. This study investigated the inhibitory activity of DVA extract against Streptococcus mutans and its biofilm.

Materials and Methods

Crude extract of the leaves was prepared using methanol. The time-kill curve for Streptococcus mutans at different concentrations of methanol extract after 6 and 24 h was determined. Biofilms of Streptococcus mutans were grown in the presence of subinhibitory concentration of extract (0.78 mg/ml) for 30 h and the bacterial counts were obtained after 6, 24 and 30 h. The chemical profile of the crude extract was obtained using gas chromatography-mass spectrometry (GC-MS).

Results

The reduction of Streptococcus mutans was concentration and exposure time dependent. The crude extract killed 48% of S. mutans at a lowest concentration of 0.1 mg/ml and 100% at 25 mg/ml after 6 h. Biofilm formation was reduced by 95, 97 and 99% after 6, 24 and 30 h of exposure to the subinhibitory concentration of crude extract respectively. GC–MS analyses revealed the presence of polyphenols such as catechin or chromene groups, chalcones with trimethoxyphenyl group and tannin with 4-O-β-D-xylopyranoside. At high concentration the crude extract was bactericidal to Streptococcus mutans but subinhibitory concentration significantly reduced the planktonic cells and biofilm formation.

Conclusions

These results suggest that this plant has the potential to be used to control S. mutans and its biofilm which are responsible for oral infections.     

In vitro antimicrobial activity of Caesalpinia ferrea Martius fruits against oral pathogens

Aim

In the Amazon region of Brazil, the fruits of Caesalpinia ferrea Martius (Brazilian ironwood) are widely used as an antimicrobial and healing medicine in many situations including oral infections. This study aimed to evaluate the antimicrobial activity of Caesalpinia ferrea Martius fruit extract against oral pathogens.

Materials and methods

Polyphenols estimation and spectral analysis (¹H NMR) of the methanol extract were carried out. The microorganisms Candida albicans, Streptococcus mutans, Streptococcus salivarius, Streptococcus oralis and Lactobacillus casei were tested using the microdilution method for planktonic cells (MIC) and a multispecies biofilm model. Chlorhexidine was used as positive control.

Results

Polyphenols in the extract were estimated at 7.3% and ¹H NMR analysis revealed hydroxy phenols and methoxilated compounds. MIC values for Candida albicans, Streptococcus mutans, Streptococcus salivarius, Streptococcus oralis and Lactobacillus casei were 25.0, 40.0, 66.0, 100.0, 66.0 μg/mL, respectively. For the biofilm assay, chlorhexidine and plant extract showed no growth at 10⁻⁴ and 10⁻⁵ microbial dilution, respectively. At 10⁻⁴ and 10⁻⁵ the growth values (mean ± SD) of the negative controls (DMSO and saline solution) for Streptococcus mutans, Streptococcus sp. and Candida albicans were 8.1 ± 0.7, 7.0 ± 0.6 and 5.9 ± 0.9 × 10⁶ CFU, respectively.

Conclusion

Caesalpinia ferrea fruit extract can inhibit in vitro growth of oral pathogens in planktonic and biofilm models supporting its use for oral infections.     

Antibacterial and cytotoxic activity of isoprenylated coumarin mammea A/AA isolated from Mammea africana

Ethnopharmacological relevance

The stem bark of Mammea africana is widely distributed in tropical Africa and commonly used in traditional medicine. This study aims to identify the active compound in Mammea africana and to evaluate its antimicrobial and antiproliferative activity.

Materials and methods

Methanol extract from the bark of the Mammea africana was separated by liquid–liquid extraction, followed by open column chromatography. A principal antimicrobial compound was purified by high performance liquid chromatography (HPLC) and its structure was elucidated by nuclear magnetic resonance spectroscopy (NMR) and mass spectrometry (MS). The antibacterial activity of the purified compound was determined using the broth microdilution method against 7 common pathogenic bacteria. The compound was also evaluated for cytotoxicity by cell proliferation assay (MTS) using the mouse embryonic fibroblast cell line NIH 3T3 and the non-small cell lung cancer cell line A549.

Results

The purified active compound was determined to be mammea A/AA and was found to be highly active against Campylobacter jejuni (MIC=0.5 μg/ml), Streptococcus pneumoniae (MIC=0.25 μg/ml), and Clostridium difficile (MIC=0.25 μg/ml). The compound exhibited significant antiproliferative activities against both NIH 3T3 and A549 cell lines.

Conclusion

Mammea A/AA isolated from Mammea africana exerts specific inhibitory activity against Campylobacter jejuni, Streptococcus pneumoniae, and Campylobacter difficile. Mammea A/AA was also found to exhibit significant cytotoxicity against both cancer and normal cell lines.     

In vitro biological activities of niloticane,a new bioactive cassane diterpene from the bark of Acacia nilotica subsp. kraussiana

Ethnopharmacological relevance

Acacia nilotica subsp. kraussiana was reported in African traditional medicine for the treatment of various ailments. Isolation of an active compound in this study from the bark extract may lead to the validation of its efficiency as a traditional crude drug.

Aims of the study

This study aimed to isolate active compound(s) from an ethyl acetate bark extract of Acacia nilotica subsp. kraussiana and to investigate some of its biological activity.

Materials and methods

The isolation process was carried out using bioassay-guided fractionation. The isolated compound was tested for antibacterial activity using the micro-dilution assay; anti-inflammatory activity using the COX-1 and COX-2 assays and investigated for inhibitory effect against acetylcholinesterase using the microplate assay.

Results

A new bioactive compound was isolated and identified as a cassane diterpene, niloticane. Niloticane showed antibacterial activity against Gram-positive bacteria Bacillus subtilis and Staphylococcus aureus with MIC values of 4 and 8 μg/mL, respectively. With Gram-negative bacteria, niloticane showed weak activity. MIC values obtained were 16 and 33 μg/mL against Klebsiella pneumonia and Escherichia coli, respectively. In the cyclooxygenase test, niloticane possessed activity with IC₅₀ values of 28 and 210 μM against COX-1 and COX-2, respectively. IC₅₀ values observed with indomethacin (positive control) were 3.6 μM for COX-1 and 189 μM for COX-2. In the acetylcholinesterase test, niloticane showed anti-cholinesterase activity with an IC₅₀ value of 4 μM. IC₅₀ values obtained by the galanthamine (positive control) was 2.0 μM.

Conclusion

The results obtained support the traditional uses of the bark of Acacia nilotica subsp. kraussiana in African traditional medicine for the treatment of some ailments that relate to microbial diseases, inflammation and central nervous system disorders.     

In vitro bactericidal activity of diterpenoids isolated from Aframomum melegueta K.Schum against strains of Escherichia coli, Listeria monocytogenes and Staphylococcus aureus

Ethnopharmacological relevance

The ethnobotanical use of Aframomum melegueta in the treatment of urinary tract and soft tissue infection suggested that the plant has antimicrobial activity.

Materials and methods

To substantiate the folkloric claims, an acetone, 50:50 acetone:methanol and 2:1 chloroform:methanol extracts were tested against Escherichia coli K12; acetone extract and the fractions of acetone extracts were tested against Listeria monocytogenes. Bioassay-guided fractionation was performed on the extract using L. monocytogenes as the test organism to isolate the bioactive compounds which were then tested against all the other organisms.

Results

Four known labdane diterpenes (G3 and G5) were isolated for the first time from the rhizomes of A. melegueta and purified. These were tested against E. coli, L. monocytogenes, methicillin resistant Staphylococus aureus (MRSA) and S. aureus to determine antibacterial activity. The result showed that two compounds G3 and G5 exhibited more potent antibacterial activity compared to the current clinically used antibiotics ampicillin, gentamicin and vancomycin and can be potential antibacterial lead compounds. The structure of the labdane diterpenes were elucidated using nuclear magnetic resonance (NMR) spectroscopy and Mass spectrometry. A possible mode of action of the isolated compound G3 and its potential cytotoxicity towards mammalian cells were also discussed.

Conclusion

The results confirmed the presence of antibacterial compounds in the rhizomes of A. melegueta with a favourable toxicity profile which could be further optimized as antibacterial lead compounds.     

Cytotoxic and antibacterial triterpenoids derivatives from Clematis ganpiniana

Ethnopharmacological relevance

The roots and rhizomes of Clematis are commonly used as an analgesic, abirritative, antibacterial, antiphlogistic, anticancer and diuretic agent. The Naxi people traditionally used Clematis ganpiniana's (Lévl. Et Vant.) as a diuretic agent, an anti-inflammatory and anticancer remedy.

Aim of study

To investigate the cytotoxic and antibacterial components from Clematis ganpiniana.

Materials and methods

The aboveground part of Clematis ganpiniana was isolated by chromatographic techniques. Structures of isolated compounds were identified by spectroscopic methods and comparison with published data. Their cytotoxic, apoptosis and antibacterial activities of purified components were also performed.

Results

By bioassay-guided fractionation techniques and chemical characterization, four triterpene glycosides were isolated and their cytotoxicity against cancer cells and antibacterial activity were tested. They showed significant inhibitory activities against MCF-7, MDA-MB-231 with IC50 value of 0.7–16.5 μg/ml, and significant apoptosis for MCF-7 and MDA-MB-231. Moreover, compound 4 showed weak wide-spectrum antibacterial activity.

Conclusion

These results provide promising baseline information for the potential use of Clematis ganpiniana as well as some of the isolated compounds in the treatment of cancer and infectious disease.     

In vitro antigonococcal activity of Coscinium fenestratum stem extract

Ethnopharmacological relevance

Gonorrhea is a sexually transmitted disease (STD), which originates from bacteria, Neisseria gonorrhoeae. It is still one of the major health problems worldwide in both men and women. Many medicinal plants have been recorded in Thai folk medicine for relieving STD but there is no scientific report of these plants for antigonococcal activity.

Aim of the study

This study was conducted to evaluate antigonococcal activity of 22 Thai medicinal plants selected from the plants popularly used in Thai folk medicine for treatment of gonorrhea.

Materials and methods

This study was performed by disc diffusion and agar dilution methods against Neisseria gonorrhoeae. Active compound was investigated by bioautographic assay.

Results

Among the selected plants, Coscinium fenestratum (Gaertn.) Colebr. extract showed the most effective activity against Neisseria gonorrhoeae ATCC 49226 with MIC value of 47.39 μg/ml. Bioautographic assay revealed that berberine was the active compound of Coscinium fenestratum against Neisseria gonorrhoeae. The average MIC values of purified berberine against Neisseria gonorrhoeae ATCC 49226 and 11 clinical isolates were 13.51 and 17.66 μg/ml, respectively while average MIC value of the crude extract of Coscinium fenestratum against all clinical isolates was about 56.39 μg/ml. There was no acute toxicity detected at the dose of 5 g of Coscinium fenestratum crude extract per kilogram.

Conclusions

These results provide theoretical support for ethnopharmacological relevance of antigonococcal activity of Coscinium fenestratum and its active compound.     

Hepatic,testicular and spermatozoa antioxidant status in rats chronically treated with Garcinia kolaseed

Ethnopharmacological relevance

Garcinia kola seed is commonly used in African Traditional Medicine as a remedy for liver disorders, hepatitis, bronchitis, throat infections as well as an aphrodisiac and fertility enhancing substance. Owing to the abundance of complex mixture of phenolic compounds in Garcinia kola seed, there is a growing safety concern on its long-term use in folklore medicine. The present study evaluated the hepatic, testicular and spermatozoa antioxidant status in rats chronically treated with Garcinia kolaseed.

Materials and methods

Adult male Wistar rats were randomly assigned to four groups of 10 rats each and were orally administered with Garcinia kola at 0, 250, 500 and 1000 mg/kg for 6consecutive weeks. Clinical observations, serum biochemistry, oxidative stress biomarkers, spermatozoa parameters and histopathological examination of the organs were assessed to monitor treatment-related adverse effects inrats.

Results

Long-term treatment of Garcinia kola had no adverse effect on the spermatozoa characteristics but significantly elevated testosterone concentration when compared to the control group. Improvement of antioxidant systems was accompanied by a significant decrease in malondialdehyde level in the liver, testes and spermatozoa of Garcinia kola-treated rats. Histological observation revealed that chronic administration of Garcinia kola had no effect on the liver and testes at all doses when compared with control.

Conclusion

Garcinia kola seed boosts the antioxidant status and exhibits no adverse effect on the liver, testes and spermatozoa after a long-term oral exposure inrats.     

Antibacterial activity of Helleborus bocconei Ten. subsp. siculus root extracts

Aim of the study

Roots of Helleborus bocconei Ten. subsp. siculus (Schiffner) Merxm. & Podl. are widely used in veterinary folk medicine in Sicily (Italy) to diagnose and cure lower respiratory tract infections in cattle. This study intended to evaluate the in vitro antibacterial activity of the methanolic root extract of Helleborus bocconei Ten. subsp. siculus, and of the bufadienolide and ecdysteroid fractions extracted from its roots, against strains belonging to species commonly associated with respiratory tract infections.

Materials and methods

The phytochemical screening of the previously prepared plant extracts was carried out by chemical, thin-layer chromatography and spectroscopic methods. The in vitro antibacterial activity of the extracts against seven different standard bacterial strains was evaluated by broth microdilution.

Results

According to the present study, Helleborus bocconei Ten. subsp. siculus roots contain bufadienolides and ecdysteroids, and the extracts containing these compounds, as well as the crude methanolic root extract, show antibacterial activity against microorganisms responsible for respiratory infections. In particular, the bufadienolide extract has the highest inhibitory activity against all the tested organisms, and, as the other extracts, shows the lowest MIC values (100 μg/ml) against Moraxella catarrhalis and Streptococcus pneumoniae.

Conclusions

Since the roots of Helleborus bocconei Ten. subsp. siculus contain substances with antibacterial activity, the traditional use of this plant may also derive from its antibacterial properties.     

Antimicrobial activity of Acacia mellifera extracts and lupane triterpenes

Ethnopharmacological relevance

Acacia mellifera (Vahl) Benth (Leguminosae) is a subtropical medicinal plant that is widely used in traditional African medicines against various diseases such as pneumonia and malaria.

Aim of the study

The present study was performed to evaluate the antimicrobial effects of extracts from the stem bark of Acacia mellifera.

Materials and methods

The extracts were examined for antibacterial and antifungal activity using the disc-diffusion method against bacterial strains: Streptococcus pneumoniae (ATCC 25923), Pseudomonas aeruginosa (ATCC 27853), Escherichia coli (ATCC 35218), Escherichia coli (ATCC 25922) and Staphylococcus aureus (ATCC 25923) and fungal strains Candida albicans (ATCC 90028), Candida krusei (ATCC 6255), Cryptococcus neoformans (ATCC 6603) and clinical isolates of Microsporum gypseum and Trichophyton mentagrophytes.

Results

Some of these extracts were found to be active against some bacterial and fungal strains and were further fractionated to give 12 pure compounds. The methanolic and methanol:dichloromethane (1:1) extracts exhibited antibacterial and antifungal activity. The two were active against Staphylococcus aureus (ATCC 25923), Microsporum gypseum, and Trichophyton mentagrophytes. Activity guided fractionation led to isolation of two active compounds: 3-(Z)-cis coumaroylbetulin and 30-hydroxylup-20 (29)-en-3β-ol which were against Staphylococcus aureus (ATCC 25923), Microsporum gypseum, Trichophyton mentagrophytes and Pseudomonas aeruginosa (ATCC 27853).

Conclusions

These results may partly explain and support the use of Acacia mellifera stem barks for the treatment of infectious diseases in traditional Kenya medicine.     

In vitro activity of Tridax procumbens against promastigotes of Leishmania mexicana

Ethnopharmacological relevance

Tridax procumbens is an active herb against leishmaniasis.

Aim of the study

Leishmaniasis is a group of diseases caused by Leishmania protozoa. We investigated the antileishmanial activity of Tridax procumbens extracts and a pure compound against promastigotes of Leishmania mexicana, the causative agent of cutaneous leishmaniasis in the New World.

Materials and methods

Extracts and (3S)-16,17-didehydrofalcarinol (1) were obtained by chromatographic methods from Tridax procumbens, and the latter identified by spectroscopic analysis. The effect of these extracts and 1 on the growth inhibition of promastigotes of Leishmania mexicana was evaluated. In order to test the safety of extracts and 1, mammalian cells were treated with them, and cell viability was assessed using trypan blue and MTT.

Results

We demonstrated that extracts of Tridax procumbens and 1 showed a pronounced activity against Leishmania mexicana. The methanol extract inhibited promastigotes growth of Leishmania mexicana with a 50% inhibitory concentration (IC₅₀) of 3 μg/ml, while oxylipin 1 exhibited the highest inhibition at IC₅₀ = 0.478 μg/ml.

Conclusions

In this study we report the biological activity of extracts and (3S)-16,17-didehydrofalcarinol (1), obtained from Tridax procumbens, on the promastigote form of Leishmania mexicana, with no effect upon mammalian cells.     

In vitro pharmacological evaluation of three Barleria species

Ethnopharmacological relevance

Various parts of Barleria prionitis L. (Acanthaceae) are used in traditional medicine to treat infection-related ailments. A comparison of their activities and knowledge of their mechanisms of action are important for drug development and conservation.

Aims of the study

This study investigated the antibacterial effects and underlying mechanisms of action of the anti-inflammatory activities of different parts of three Barleria species of South African origin.

Materials and methods

Crude extracts of different parts of three Barleria species were investigated in vitro for their biological activity. Antibacterial activity was evaluated using the micro-dilution assay against two Gram-positive and two Gram-negative bacteria. Anti-inflammatory activity was evaluated using the cyclooxygenase COX-1 and COX-2 assays.

Results

All the extracts showed broad-spectrum antibacterial activity with minimum inhibitory concentrations ranging from 0.059 to 6.25 mg/ml. Twelve out of 21 crude extracts evaluated showed good activity (>70%) in the COX-1 assay while 10 extracts showed good activity in the COX-2 assay. All the petroleum ether extracts (except B. prionitis stem) exhibited good inhibition of prostaglandin synthesis in COX-1.

Conclusion

The results demonstrated the therapeutic potential of these plants as antibacterial and anti-inflammatory agents. Their anti-inflammatory properties are mediated by the inhibition of the cyclooxygenase enzymes.     

Cytotoxic activity of 9,10-dihydro-2,5-dimethoxyphenanthrene-1,7-diol from Eulophia nuda against human cancer cells

Ethnopharmacological relevance

Eulophia nuda L. (Orchidaceae) is a medicinally important terrestrial orchid used for the treatment of tumours and various health problems by the local healers throughout the Western Ghats region in Maharashtra (India).

Aim of the study

To isolate the active molecule from Eulophia nuda and to study its cytotoxic potential against human cancer cells.

Materials and methods

The crude methanolic extract of Eulophia nuda tubers was fractionated by stepwise gradient of the solvents—chloroform–methanol to isolate the pure compound. Isolated pure compound was assessed for its cytotoxic potential against human breast cancer cell lines, MCF-7 and MDA-MB-231 using MTT assay. Structure elucidation of the isolated active compound was carried out by extensive spectroscopic analysis including ¹H NMR, ¹³C NMR, NOESY, COSY, LC–MS and IR.

Results

The isolated active molecule was identified as phenanthrene derivative 9,10-dihydro-2,5-dimethoxyphenanthrene-1,7-diol. This compound showed good antiproliferative activity against human breast cancer cell lines MCF-7 (91%) and MDA-MB-231 (85%) at 1000 μg/ml concentration.

Conclusion

9,10-Dihydro-2,5-dimethoxyphenanthrene-1,7-diol from Eulophia nuda tubers showed good growth suppressive effect against human cancer cell lines MCF-7 and MDA-MB-231 making it a potential biomolecule against human cancer.     

Chemical composition and antimicrobial activity of Phyllanthus muellerianus (Kuntze) Excel essential oil

Ethnopharmacological relevance

Phyllanthus muellerianus (Kuntze) Excel (family Euphorbiaceae) stem bark is used in Cameroon by Baka pygmies as a remedy for wound healing and tetanus.

Aim of the study

To characterize the chemical composition and to evaluate the antimicrobial properties of the essential oil of the plant.

Materials and methods

The essential oil was extracted from the stem bark by dynamic head space and by hydrodistillation and characterized by GC and GC-MS analyses. The antimicrobial activity was evaluated on the basis of the minimum inhibitory concentration (MIC) and the minimum bactericidal–fungicidal concentration (MBC–MFC) by the micro and macrodilution methods. The following bacteria and fungi were used: Clostridium sporogenes ATCC 3584, Staphylococcus aureus ATCC 6538, Streptococcus mutans ATCC 25175, Streptococcus pyogenes ATCC 19615, Escherichia coli ATCC 10536, Candida albicans ATCC 10231, Candida albicans LM 450, Trichophyton mentagrophytes LM 230, Trichophyton rubrum LM 237, Microsporum canis LM 324.

Results

The hydrodistillation afforded 0.06% (dry weight basis) of pale yellow oil. Thirty-eight compounds representing 90.69% were identified. The major component (36.40%) was found to be (E)-isoelemicin, identified by comparison of its ¹H-NMR experimental data, with literature data. The oil showed good antibacterial activity against Clostridium Sporogenes, Streptococcus mutans and Streptococcus pyogenes with MIC ranging from 13.5 to 126 μg/ml. A weak antifungal activity (MIC 250 μg/ml) was found against Trichophyton rubrum, only.

Conclusions

The antimicrobial activity and the chemical composition of Phyllanthus muellerianus stem bark essential oil are reported for the first time.     

Davilla elliptica and Davilla nitida: Gastroprotective,anti-inflammatory immunomodulatory and anti-Helicobacter pylori action

Ethnopharmacological relevance

Davilla elliptica and Davilla nitida are species commonly found in the Brazilian Cerrado biome.

Aim of the study

Based on ethnopharmacological and phytochemical analyses, methanolic extracts from leaves of Davilla elliptica (EDE) and Davilla nitida (EDN) were evaluated for their anti-ulcer, anti-inflammatory, immunological and anti-Helicobacter pylori activities.

Materials and methods

The gastroprotective action of both extracts was evaluated in rodent experimental models (HCl/ethanol, ethanol or NSAID). We also evaluated anti-inflammatory (carrageenin-induced rat hind paw edema), immunomodulatory (murine peritoneal macrophages) and antibacterial action of both extracts against a standard strain of Helicobacter pylori.

Results

EDE and EDN (500 mg/kg) were able to protect gastric mucosa against HCl/ethanol solution (EDE 63%; EDN 59%), absolute ethanol (EDE 95%; EDN 88%), and also against injurious effect of NSAID (EDE 77%; EDN 67%). When EDE and EDN were challenged with sulfhydryl depleter compound, the gastroprotective action of both extracts was completely abolished. EDE had gastroprotective effect related to increase of glutathione bioavailability and stimulated higher levels of NO, H₂O₂ and TNF-α production. Otherwise EDN showed better anti-Helicobacter pylori action than EDE. Neither extracts presented anti-inflammatory activity by oral route.

Conclusion

The phytochemical investigation showed that both extracts possess phenolic acid derivatives, acylglycoflavonoids and condensed tannins with evident quantitative variations that probably influenced the pharmacological differences between extracts.     

Isolation and identification of antibacterial and cytotoxic compounds from the leaves of Muntingia calabura L.

Ethnopharmacological relevance

Muntingia calabura (Elaeocarpaceae) is one of the most common roadside trees in Malaysia. Its leaves, barks, flowers and roots have been used as a folk remedy for the treatment of fever, incipient cold, liver disease, as well as an antiseptic agent in Southeast Asia. The aim of this study is to isolate and identify the antibacterial and cytotoxic compounds from the leaves of Muntingia calabura L.

Materials and methods

Antibacterial and cytotoxic activities were determined by micro-broth dilution and MTT assays, respectively. Seven fractions (F1–F7), three flavones and a chalcone were isolated from the active EtOAc extract using bioassay-guided screening. The structures of four compounds were elucidated by spectroscopic methods and compared with published data. The compounds were further tested for their antibacterial and cytotoxic activities.

Results

Three flavones and a chalcone [5,7-dihydroxy-3,8-dimethoxyflavone (1), 2′,4′-dihydroxychalcone (2), 5-hydroxy-3,7-dimethoxyflavone (3) and 3,5,7-trihydroxy-8-methoxyflavone (4)] were isolated from the active fraction F5 of EtOAc extract. Compounds 1 and 3 were isolated for the first time from Muntingia calabura L. Antibacterial activity indicates that compound 2 exhibited the most significant activity with MIC value of 50 μg/mL and 100 μg/mL against MSSA and MRSA, respectively. Cytotoxic activity indicates that compounds 2 and 3 exhibited very strong activity against HL60 with IC₅₀ values of 3.43 μg/mL and 3.34 μg/mL, respectively.

Conclusion

The antibacterial activity of the leaves of Muntingia calabura L. is ascribable to the active compound 2 while the cytotoxic activity is ascribable to the active compounds 2 and 3.     

Active constituents from Sophora japonica exhibiting cellular tyrosinase inhibition in human epidermal melanocytes

Aim of the Study

There is greater consumer awareness of plant-based skin-care products. Sophora japonica L. (Fabaceae) has been used traditionally as a hemostatic agent and also has skin-care and whitening benefits. The effect of the isolated active compounds of Sophora japonica L. (Fabaceae) that inhibits tyrosinase activity in human epidermal melanocytes (HEMn) was examined.

Materials and methods

We used the mushroom tyrosinase inhibitory assay to isolate active constituents from the extracts. The structures of these constituents were characterized by physical and spectroscopic analyses. Cellular tyrosinase kinetics were analyzed and showed by Lineweaver–Burk plot.

Results

A new compound, N-feruloyl-N′-cis-feruloyl-putrescine (8), together with four flavonoids and three putrescine derivatives were obtained after assay-guided isolation of S. japonica. In HEMn, compound 8 was minimally cytotoxic (cell viability >90% at 100 μM) and the IC₅₀ value for suppression of cellular tyrosinase activity was estimated as 85.0 μM. Zymography analysis demonstrated the compound's concentration-dependent effects and the kinetic analysis indicated the compound's mixed-inhibitory action.

Conclusions

We concluded that the new compound 8 is the most potent component of S. japonica yet discovered. Its pigment inhibition activity may be exploitable cosmetically.     

Essential oils of Salvia bracteata and Salvia rubifolia from Lebanon: Chemical composition,antimicrobial activity and inhibitory effect on human melanoma cells

Aim of the study

Salvia bracteata Banks et Sol. and Salvia rubifolia Boiss. are known in folk medicine of Lebanon for the treatment of microbial infections, cancer, urinary and pulmonary problems. In the present study the chemical composition and antimicrobial activity of essential oils from aerial parts of Salvia bracteata and Salvia rubifolia collected in Lebanon were evaluated. The oils were also tested for their potential antiproliferative effects against M14 human melanoma cells.

Material and methods

The oils were studied by GC and GC–MS and their antibacterial activity (MIC and MBC) was tested against ten bacteria species using the broth dilution method. The inhibitory effect on human melanoma cells (measurement of cell vitality, cell membrane integrity and genomic DNA fragmentation) was studied using MTT assay, calculation of LDH release and COMET assay.

Results

The oils showed a good antibacterial activity (MIC = 50 μg/ml) against Gram+ bacteria. They besides exhibited an inhibitory effect on the human cancer cells examined inducing also apoptotic cell death, but the oil of Salvia rubifolia was significantly (p < 0.001) more active as compared to the oil of Salvia bracteata.

Conclusion

The results on the pharmacological activities of these Salvia species provide an in vitro scientific support for the use of these plants in traditional herbal preparations.     

In vitro antibacterial effects of Cinnamomum extracts on common bacteria found in wound infections with emphasis on methicillin-resistant Staphylococcus aureus

Ethnopharmacological relevance

Cinnamomum species have been widely used in many traditional systems of medicine around the world. In the Malaysian traditional system of medicine, the leaves, stem bark and stem wood of Cinnamomum iners, Cinnamomum porrectum, Cinnamomum altissimum and Cinnamomum impressicostatum have been used to treat wound infections. To study the antibacterial effects of Cinnamomum iners, Cinnamomum porrectum, Cinnamomum altissimum and Cinnamomum impressicostatum against common bacteria found in wound infections with primary focus on methicillin-resistant Staphylococcus aureus (MRSA).

Materials and methods

The crude extracts from the leaves, stem-bark and stem-wood of Cinnamomum iners, Cinnamomum porrectum, Cinnamomum altissimum and Cinnamomum impressicostatum were obtained using sequential extraction with hexane, ethylacetate, methanol and water. The volatile oils were obtained by hydro-distillation. The antibacterial activities of extracts were investigated using disk diffusion assays and broth microdilution assays.

Results

The volatile oils obtained from the stem-bark of Cinnamomum altissimum, Cinnamomum porrectum and Cinnamomum impressicostatum have shown significant antibacterial activity against a wide range of Gram positive and Gram negative bacteria including MRSA. A few test extracts have shown better activity against MRSA as compared to methicillin sensitive Staphylococcus aureus (MSSA). Amongst all the test extracts, Cinnamomum impressicostatum stem-bark water extract produced the largest inhibition zone of 21.0 mm against MRSA while its inhibition zone against MSSA was only 8.5 mm. The minimum inhibitory concentration (MIC) of this extract against MRSA was 19.5 μg mL⁻¹ and the corresponding minimum bactericidal concentration (MBC) was 39.0 μg mL⁻¹.

Conclusions

This study has scientifically validated the traditional use of Cinnamomum species in treating wound infections. Of high scientific interest was the observation that the antibacterial effect of Cinnamomum impressicostatum stem-bark crude water extract against MRSA was significantly higher than its effect against MSSA, suggesting that the extract contains a compound(s) with higher specific neutralising activity against the drug resistance markers of MRSA.     

Decoctions from Citrus reticulata Blanco seeds protect the uroepithelium against Escherichia coli invasion

Ethnopharmacological relevance

Traditional usage suggests Citrus reticulata Blanco seeds have beneficial effects against infection. The purpose of this study was to investigate the effect of Citrus reticulata on the uroepithelium and to determine the mechanisms responsible for protection against urinary tract infection (UTI).

Materials and methods

Human bladder cell lines T24 and 5637 were employed in a cell culture infection model to determine the effects of Citrus reticulata treatment on Escherichia coli adherence and invasion of the uroepithelium. β1 integrin and caveolin-1 mRNA expression was assessed using RT real-time PCR. β1 integrin protein expression was confirmed by Western Blot. The effect of Citrus reticulata on bacteria was investigated using antibacterial sensitivity, yeast agglutination and biofilm assays.

Results

Citrus reticulata treatment decreased β1 integrin expression and reduced bacterial invasion while adhesion of uroepithelial cells was not affected. Caveolin-1 expression was not influenced either and Citrus reticulata did neither exhibit any direct antimicrobial effect nor interfered with type 1 fimbriae binding.

Conclusions

Our results show that Citrus reticulata has a protective effect on the uroepithelium as seen by reduced bacterial invasion of uroepithelial cells. These properties suggest that seeds from Citrus reticulata may have therapeutic potential in preventing UTI.